Climate

• Long-term conditions in an area
  • Four physical factors— temperature, precipitation, sunlight, and wind
• Climograph: plot of the annual mean temperature and precipitation in a particular region

Global Climate Patterns

• Determined largely by the input of solar energy (differential heating of Earth’s surface) and Earth’s movement in space

Effects on Climate

Seasonality

• Changes in wind pattern affect ocean current

Bodies of Water

• Water’s high specific heat helps regulate local temp → less extreme temp
• Ocean currents influence climate along the coasts of continents by heating or cooling overlying air masses that pass across the land.

• Ex: Coastal regions are also generally wetter than inland areas at the same latitude.

Mountains

• Affect amount of sunlight that reach ground → affect local temp, air flow, and rainfall
• When warm, moist air approaches a mountain, the air rises and cools, releasing moisture on the windward side of the peak
• On the leeward side, cooler, dry air descends, absorbing moisture and producing a “rain shadow” → determine where deserts are found
• South-facing slopes in the Northern Hemisphere receive more sunlight than north-facing slopes and are therefore warmer and drier → determine local distribution

Vegetation

• Forests dark in color absorb more and reflects less solar energy → warm Earth’s surface in forested areas
  • Warming effect balanced by transpiration

Aquatic Biomes

• Unlike terrestrial biomes, aquatic biomes are characterized by their physical environment rather than by climate and are often layered with regard to light penetration & temperature
• Very big, so impact biosphere
  • ex: produce oxygen, source of rainfall, effects on ocean temp on global climate and wind patterns

Zonation

• Photic zone: region where there is sufficient light for photosynthesis
• Aphotic zone: little light
• Abyssal zone: deep in aphotic zone
• Benthic zone: bottom of all zones
• Where light penetrates = warm. No light = cold
  • Thermocline: layer of abrupt temperature change which separates uniform warm upper layer from cold deeper layer
• Turnover: semiannual mixing of lake waters as a result of seasonal changing of water density
  • Sends oxygenated water from a lake’s surface to the bottom and brings nutrient-rich water from the bottom to the surface in both spring and autumn

Dispersal and Distribution

• Dispersal: movement of individuals or gametes away from their area of origin or from centers of high population density
  • Contributes to global distribution of organisms
• Range expansion: when organisms reach an area where they did not exist previously
  • Successful = potential range is larger than actual range
• Increasing greenhouse gas concentrations in the air are warming Earth and altering the distributions of many species.
  • Some species will not be able to shift their ranges quick enough to reach suitable habitat in the future

Effects on Organism Distribution

Biotic & Abiotic Factors

• Abiotic (nonliving) factors like temp, light, water, and nutrients & biotic factors influence organism distribution, size, and biodiversity

Biotic Factors

• Ability of a species to survive and reproduce is reduced by its interactions with other species, such as predators or herbivores
  • Also presence/absence of pollinators, food resources, parasites, pathogens, and competing organisms
• Primary producers & dominant predators support diversity in ecosystems
  • Primary Producers: Provide food, shelter, reduce erosion
  • Predators: keep prey populations in control, diverse diets that don’t put too much pressure

Abiotic Factors

Temperature

• Cells may rupture if the water they contain freezes; at higher temp → more radiation → damage DNA and denature proteins
• More sunlight & nutrients → more primary production; also more water more species
  • All increase diversity
• Organisms typically function best within a specific range of environmental temperature
  • Temp outside range = more energy

Water and Oxygen

• Water affects oxygen availability in aquatic environments; more water → more species

Salinity

• Affects water balance bcuz of osmosis

Biomes

• Biomes: regions of the biosphere that exhibit common environmental characteristics.
  • Each has unique communities or ecosystems of plants and animals that share adaptations to survive

Major Biomes

1. Tropical rain forests: characterized by high temperature and heavy rainfall; tall trees that from thick canopy that reduces light penetration
2. Savannas are grasslands with scattered trees.

• Tropical → high temp but lot less water than rain forests

1. Temperate grasslands receive less water and lower temperatures than savannas.
2. Temperate deciduous forests have warm summers, cold winters, and moderate precipitation.

• Deciduous trees shed their leaves during the winter → adaptation to poor growing conditions (short days and cold temperatures).

1. Deserts are hot and dry → located where air masses are descending

• Adaptations: plants with leathery leaves or spines (cacti); animals have thick skins and restrict their activity to nights.

1. Taigas are characterized by coniferous forests (vegetation with needles for leaves). Long and cold winters with precipitation is in the form of snow.
2. Tundras have winters so cold that the ground freezes

• During summer, the upper topsoil thaws and supports grassland community (vegetation tolerant to soggy soil)
  • But the deeper soil, the permafrost, stays frozen (growth limiting factor)

1. Freshwater biomes include ponds, lakes, streams, and rivers.
2. Marine biomes include estuaries (where oceans meet rivers), intertidal zones (where oceans meet land), continental shelves (shallow oceans that border continents), coral reefs (masses of corals that reach the ocean surface), and the pelagic ocean (the deep oceans)

Trophic Levels                                                                                                                         

• Trophic Levels: position organism is in food chain
  • Way of illustrating energy flow and production & utilization of energy

1. Primary produces: photoautotrophs that convert sun energy into chemical energy → ecosystem’s initial source of energy
2. Primary consumers: (herbivores) heterotrophs that eat primary producers
3. Secondary consumers: (primary carnivores) heterotrophs that eat primary consumers
4. Tertiary consumers: (secondary carnivores/Apex) heterotrophs that eat secondary consumers
5. Detritivores: heterotrophs that get energy by consuming dead plants and animals (detritus)

• Decomposers: smallest detritivores (ex: fungi and bacteria)
  • Recycle chemical elements to producers and important bcuz convert organic matter from all trophic levels to inorganic compounds usable by primary producers.
  • If decomposition stopped, life would cease as detritus piled up and the supply of ingredients needed to synthesize organic matter was exhausted.

Trophic Interactions

• Certain species in community can influence the dynamics of that community

1. Foundation Species: strong effects on communities bcuz of large size or abundance
2. Dominant Species: most abundant species that contributes greatest biomass to a community

• Species dominant bcuz is best able to compete for resources & escape predators/disease

3. Keystone species: have strong, disproportionate influence on the health of a community or ecosystem their relative to abundance

• Removal of keystone species results in collapse in food webs and ecosystems; leads to decrease in species diversity
  • May eat species that eat another species

4. Invasive Species: introduced species that proliferates and displaces native species bcuz it is a better competitor and/or because natural predators/pathogens are absent

• Kudzu: climbing vine that kills vegetation by blocking sun
• Potato blight: caused by fungus-like protist

Influences on Number and Size of Trophic Levels in Ecosystems

1. Size of bottom trophic levels: bcuz primary producers provide initial source of energy to the ecosystem, their number and generated biomass control how many trophic lvls can be supported

• So ecosystem with small tier of primary producers cannot sustain many tiers above it

1. Efficiency of energy transfer between trophic levels: ~10% of energy passed from one lvl to another → energy loss limits number/size of trophic lvls and abundance of top carnivores

• Ecosystems (like in tropical rainforests) have higher photosynthetic efficiency → longer food chains → more complex food webs

1. Stability of trophic levels: ecosystems with long food chains have less stable trophic levels bcuz bcuz there are more lvls below them that can be weakened by environmental changes
2. Requirements of top predators: top tier size is limited bcuz of less biomass available and high energy requirements of large, top predators

Trophic Levels Models

• Size of trophic levels can also be regulated by interactions between the levels
  • Organisms can be controlled by what they eat (“bottom-up” control) or by what eats them (“top-down” control).

1. Bottom-up model: structure of trophic lvls are regulated by changes in the bottom trophic lvl

• Ex: primary productivity low → few supported trophic lvls

1. Top-down model: structure of trophic levels are regulated by changes in the top trophic level

• Ex predator removed → herbivores increase → primary producers decrease → total biomass decreases
• Top down regulation can become irregular when humans remove top predators

Ecological Pyramids                                                                                                                                                       

• Used to show relationship between trophic levels
• Tiers represent sizes of trophic levels
  • Each represented in terms of energy (A.K.A productivity), biomass, or number of organisms
• Tiers are stacked upon one another in order of which energy is transferred between levels
  • Aquatic ecological pyramids are often inverted because biomass of consumers exceeds that of producers